The present invention departs from problems recognized at so-called “wireless microphones”. We understand under a wireless microphone a system consisting of a transmitter unit with an input microphone arrangement and of a hearing device with a respective wireless receiver.
Audio signals perceived by the microphone arrangement of the transmitter unit, remote from the hearing device and e.g. carried at an individual's belt are wirelessly transmitted to the receiver of individual's hearing device, by means of a carrier frequency signal modulated with the audio signal as is perceived by the microphone.
In the hearing device, the audio-signal-modulated carrier frequency signal is demodulated and the audio signal recaptured is operationally connected to an electrical to mechanical converter of the hearing device, as to a loudspeaker unit.
Nevertheless, the problems and objects defined over such a system do also apply to other wireless transmitter units than those forming a part of wireless microphone systems, and the present invention therefore presents also solutions for such other wireless transmitters.
Wireless transmitters often have the option to transmit via their antennas on one hand with different, selectable carrier frequencies within one frequency band, but also within different frequency bands, also called channels. The frequency bands usable of such transmitters are usually hardwired within the transmitter and may be changed by means of switches.
Nevertheless, a lot of countries legally restrict the frequency bands, which may be used for instance without special permission and additionally often also limit the power, i.e. the effectively radiated power (ERP) for transmitted signals, which do not require such special permission fee or tax. These restrictions are often different from country to country.